OK so I've been reading up on performance cars and, as usual, all the mags and blogs have some kind of Mustang/Camaro comparison test.

And it always comes down to complaining about the Camaro's weight and the Mustang's solid axle.

So here's where I'm getting confused... why is a solid axle really such a problem? I look at road-course cars and hi-po drift cars with independent rear suspension. and they all end up with massive anti-sway/anti-roll bars installed. How do these not affect performance in the same way having a live axle would?

I can understand the suspension setups making a difference, but once you get to the point where you're tethering the wheels together again, isn't that effectively doing the same thing as a solid axle?

Maybe I'm confused, or maybe I'm jaded because I have a solid axle in my Vic and it "handles" plenty fine... (as well as a 5000lb boat can handle, anyway). I know Ford's stuck with it because of cost/reliability/because a Mustang always has a solid axle, and they've really made it work to their advantage...

I just don't get why IRS is such a big deal when to gain back performance you have to engineer weird half-shafts and then put in huge stiff swaybars and such.

Personally I prefer a solid axle on a rwd car. Dunno about everyone else here.

Even a thick anti-roll bar won't create a handling setup reminiscent of a live axle, at least to an extent.

The characteristic that sets IRS and live axle apart is the fact that live axles leave very little control over camber change. The wheels are tethered together usually perfectly perpendicular to the road surface. When one hits a bump, it gets a sudden burst of negative camber while the opposite wheel is at positive camber, reducing both tires' contact patches and grip.

The only non-live axle suspension type that exhibits this characteristic is the quasi-independent deDion tube suspension.

The benefit of an IRS is that camber can be set on each wheel independently of the other, and upon bump or rebound neither will have a camber change unless the suspension links are designed to alter camber when the wheel moves vertically.

When well setup, a live-axle really doesn't give up much - if any - performance to an IRS.

The authors of the magazine articles in question bitch about it because the Mustang is a road-car, which inherently means its suspension setup is compromised and not optimized, hence the bitching.

one thing with my Capri when you hit a hump in the road during a corner, odd things happened dynamically, the car moved in an unexpected fashion. The Merkur XR4Ti i had was an IRS and in the corners you could push and push and push and push, but at the limit, it was way less forgiving than my Capri.

Thanks for the thoughts, guys... its interesting because the latest comparo was between the ZL1 and the Boss 302 Laguna Seca model.

The long and the short of it came down to that the Camaro needed 135 more horsepower, IRS, and fancy magnetic-ride suspension to finally be better than the Mustang... when they go on to describe this ridiculously fat swaybar on the ZL1. Wut?

It's interesting to me... I need to borrow/rent something with IRS to see what it's like by comparison.

its the styling and the fact that I had always wanted a Camaro.
A Mustang is nice, though.

Ive only owned 2 cars with IRS and have nothing but good to say so far. The 85 w123 mercedes handled very well for a tank and the 95 bimmer i drive now takes corners and asks for more.

I've always been partial to IRS- I had an '85 Rx-7 (live) and an '89 BMW 325is (IRS) at the same time, and the BMW would drive circles around the Rx-7.

Solid rear axles = evil handling attributes, which can be controlled & mitigated by Panhard rods, de Dion links, and other low-end kludges, but they remain a solid rear no matter what you do, and will always result in nasty side-stepping on bumps mid-corner.

IRS = simply eliminates most dynamic force transference from side-to-side. Do not confuse roll-bar anchor points with axle mounts, they do not transfer load like a solid rear does and their twisting moment is very different.

For trucks, other load carrying vehicles (such as Mustangs coming back from McDonalds, wagons, and similar) the solid rear end is a cheap effective installation.

For maximum performance, an increase in safety, a fully independent rear is preferred. The only time a solid rear end car wins a race is when it is racing against similarly handicapped suspensions.

They used to fit solid fronts to cars for the same reasons...

I know from talking with some former AMC/Jeep Engineers I have met at some car shows (I go to some once in a while), they all tell me that while IRS and IFS are all great and fancy, the performance per dollar based on the sheer simplicity of solid axles can't be beat.

Posted by Samurai one thing with my Capri when you hit a hump in the road during a corner, odd things happened dynamically, the car moved in an unexpected fashion. The Merkur XR4Ti i had was an IRS and in the corners you could push and push and push and push, but at the limit, it was way less forgiving than my Capri.

you had an xr4ti??? i used to drool on those things in the day

Posted by Agent Skelly I know from talking with some former AMC/Jeep Engineers I have met at some car shows (I go to some once in a while), they all tell me that while IRS and IFS are all great and fancy, the performance per dollar based on the sheer simplicity of solid axles can't be beat.

What?

Posted by bandi What?

I guess what they are trying to say was that solid axles are the best bang for your buck on most vehicles just because of not many components over an IRS or even an IFS system.

Posted by Agent Skelly I guess what they are trying to say was that solid axles are the best bang for your buck on most vehicles just because of not many components over an IRS or even an IFS system.

That sounds like BS in an attempt to justify poor design attributes. Sure, they are OK for heavy load carrying trucks, that traverse smooth roads, but anything else and they are old, old, technology.

Not like the US car industry is viable anyway, so no surprise someone in it would attempt to justify 100 year old technology as 'adequate'!

Neko.

Thanks for the schooling, gents!

Skelly - I've heard the same thing from a guy who used to work at GM... he said all the boats (Caprice, etc.) kept the solid axle at both GM and at Ford because it was hard to beat the performance for the cost. Then they'd just tinker with the suspension setups to improve handling.

Posted by Agent Skelly I guess what they are trying to say was that solid axles are the best bang for your buck on most vehicles just because of not many components over an IRS or even an IFS system.

I dunno, people talk like not having a solid axle means infinite amounts of maintenance and more components to wear out, but in reality, I've rebuilt a lot more differentials in solid axle vehicles than anything independent.

Posted by nostra-YOUPPI! you had an xr4ti??? i used to drool on those things in the day

i had a red 86 with an autospastic.
the transmissions in them were fucking junk. Instead of sourcing the precious T5 away from the Mustang Turbo GT, SVO, Thunderbird T-coupe and Cougar XR7, they stuffed in a Pinto 4-speed, added overdrive and said good enough. The car was too damn heavy and overpowered for a halfway transmission and they broke. This carried to the automatic-equipped cars. Ford used the C3, which again, was too damn small for the job and predictably they failed.
My was rebuilt before I got it, but still blew.

All the car basically was was a left-hand drive Ford Sierra XR4 with a 2.3L Turbo under the hood.
BUT... it was fun, weird and no one knew what it was. I only had the car for a short period before the transmission said goodnight.

Posted by bandi I dunno, people talk like not having a solid axle means infinite amounts of maintenance and more components to wear out, but in reality, I've rebuilt a lot more differentials in solid axle vehicles than anything independent.

Its not so much an maintenance issue with IRS/IFS but rather an engineering issue. I know none of you guys have an interest in automotive R&D as I do, but designing and tuning an independent suspension costs a bit more than using live axles, BUT the driving factor in spending the money by the auto makers is customer demand for smoother ride, able to cope with high speed turns, and etc differing what market the car is in.

What's funny is that back in the day, the Camaro (82-2002), used a straight axle and was ridiculously stable. You really had to be an idiot to lose an F-body on a twist road/course and that was i think due to road hugging girth and a not so badly engineered half-assed suspension. I mean, have any of you driven an F-body and then driven a Mustang/Capri on the same road? The Camaro is unflappable.

Posted by Agent Skelly Its not so much an maintenance issue with IRS/IFS but rather an engineering issue. I know none of you guys have an interest in automotive R&D as I do, but designing and tuning an independent suspension costs a bit more than using live axles, BUT the driving factor in spending the money by the auto makers is customer demand for smoother ride, able to cope with high speed turns, and etc differing what market the car is in.

Or.... Jeep uses it, so it's the best?